In recent years, the number of high performance terminal devices each having performance equivalent to that of a personal computer is increasing, whereby an amount of data per user is also increasing. As the amount of data increases, competition for a radio resource and the like occurs among users positioned in the same base station area, whereby a reduction of a communication speed and the like occurs.
As a technique of suppressing the reduction of the communication speed and the like, downsizing of a cell in the base station has been implemented. Specifically, a communication capacity per unit area has been increased by downsizing a wireless area covered by one base station, and also by increasing the number of base stations within the same wireless area. (See, for example, Japanese Laid-open Patent Publication No. 2006-270180 and Japanese Laid-open Patent Publication No. 2011-166274).
The above-described technique, however, have a problem in that handover frequently occurs, whereby traffic of a control signal due to the handover increases, and a load on a wireless network increases.
For example, the handover occurs more frequently to a mobile terminal such as a portable terminal because an area, which has been one wireless area before, now extends over multiple cells due to downsizing of the cell of the base station.
In a case where the handover is performed between base stations due to moving of the terminal, in order to switch the base station to communicate, a control signal used in the handover is transmitted and received between a Mobility Management Entity (MME) and the base station, and between the MME and the terminal. That is, the number of handover between the base stations is increased due to the downsizing of the cell. Accompanied by this, the traffic of the control signal in the MME is increased, and as a result, a load on the wireless network is increased.